<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>canvas</title>
    <style type="text/css">
      .container{
        width: 200px;
        height: 200px;
      }
    </style>
</head>
<body>
    <div class="container">
      <canvas id="target" width="200px" height="200px"></canvas>
    </div>
    <script type="text/javascript">
      window.onload = function(){
        drawLine();
      }
      function drawLine(){
        const radio = 0.8;
        const canvas = document.querySelector('#target');
        const context = canvas.getContext('2d');
        context.strokeStyle = 'red';
        context.lineWidth = 2;
        context.beginPath();
        context.moveTo(0, 0);
        context.quadraticCurveTo(0*radio,100*radio,100,100);
        context.stroke();
      }
    </script>
</body>
</html>